Ah, the Middleton sisters. While Kate Middleton is—as she should be—all decorum, royal protocol and generally concerned with being prim and looking proper at all times, Pippa Middleton obviously has a little more freedom in both her style and behavior.

And over the weekend, she took full advantage of that fact, turning both up to red-hot.

The Duchess of Cambridge's little sis was among the high society guests at the Boodles Boxing Ball, the annual charity boxing match favored by anyone with a title and an upright pinky, and it's safe to say she blew the sartorial competition right out of the water.

Looking sultry in a plunging red satin gown and Wilbur and Gussie gold clutch, she may have arrived on her own, but she certainly didn't leave that way.

Instead, the 28-year-old was joined by former cricketer-turned-financier beau Alex Loudon, and the duo couldn't have seemed happier to reunite, as the couple was spotted engaging in a smoochtastic PDA outside the venue at 4:30 a.m.

Meanwhile, in addition to Pippa and Alex, among the other 850 guests at the ball (which raised around $154,000 for charity), included former Spice Girl Geri Halliwell (who wore a strikingly similar dress to Pippa…bad luck for her), Princesses Beatrice and Eugenie, Prince Harrys former girlfriend Chelsy Davy, and—potentially awkward alert—Prince William's ex Jecca Craig.